Species Of The Week Number 19: Common Earthworm

When I was 6 I actually had an earthworm called Phillip, I kept him in a matchbox. I now know this was a mistake.

Earthworms' bodies are long tubes made up of ring-like segments called annuli which are covered in little hairs which the worm uses to move and burrow. You may notice a thicker lumpy bit in the middle of the adult worm's body. This is not scar tissue where the worm has been cut in half - but a thing called a clitellum where it stores its eggs.

All adult worms have a clitellum because they are hermaphrodite - ie they are both male and female (I told you it was a mistake to call my worm Phillip, I misgendered it). The clitellum is always nearer the head than the tail - which is handy as its otherwise hard to tell which end to talk to.

Earthworms are all heart. In fact they have 5 hearts. They also have light sensitive cells but no eyes.

Charles Darwin spent thirty years studying earthworms and wrote a book about them. He said "There are few animals which have played so important a part in the history of the world than the earthworm." This is because they break down organic matter, and give structure to soil so it drains better.

How many earthworms are there in the Meanwood Valley? Well. The lowest general estimate I can find is 250,000 per acre. I guess there are maybe 100 acres of undeveloped land in the footprint of the Meanwood Valley Bioblitz? So there could be at least 2.5 million here.

I miss 'Phillip'.

Posted on 01 February, 2023 16:15 by clunym